AAWSAP DIRD, High-Frequency Gravitational Wave Communications, April 2010

This Defense Intelligence Reference Document, DIA-08-1004-005, is dated 6 April 2010. The Defense Intelligence Agency's Defense Warning Office prepared it under the Advanced Aerospace Weapon System Applications program. It reviews proposed laboratory generators and detectors for high-frequency gravitational waves. It favors a piezoelectric approach for proof-of-concept tests, IR-excited molecules for an operational transmitter and the Li-Baker detector as the receiver. It estimates about 1.9 million bits per second over 7,000 km through the Earth and discusses timing standards and interplanetary navigation uses.

From the source: Release of 2026-09-18 Incident: 4/6/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD examines whether high-frequency gravitational waves could serve as a communications medium while avoiding the attenuation that limits radio-frequency systems. The report surveys proposed transmitter and detector concepts, argues that gravitational-wave communications could support secure point-to-point links, timing standards, and interplanetary navigation, and gives particular attention to laboratory generator concepts and the Li-Baker detector as possible building blocks for such a system. The document makes clear, however, that the entire concept depends on capabilities that had not been demonstrated in practice, including laboratory-scale generation and reliable detection of usable high-frequency gravitational-wave signals. It is an exploratory systems-oriented review built around a future communications concept.

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According to Cruise (2008) of Birmingham University its frequency is limited to 100 MHz
and at higher frequencies its sensitivity diminishes. In the case of the Infrared-excited
molecules approach, on might employ a variant of the Robinson Gravitational Wave
Background Telescope for the receiver or detector (Yoon, et al., 2006). It is a
bolometric large angular scale Cosmic Microwave Background (CMB) polarimeter, but
might possibly be modifiable for direct HFGW detection.
Development of 100MHz GW detectors
at N ational Astronomical Observatory of
Japan
Two synchronous recycling
interferometers were built!
S y nchronous recy cling Interferometer (Concept: Drever 1983)
Figure 11. The National Astronomical Observatory of Japan 100 MHz Detector
2.2.2 Concept (Li-Effect)
The Li-Effect was first published in 1992 and subsequently, some nine peer-reviewed
papers have been published concerning it including a capstone paper, Li, et al. (2008)
included as Appendix C. The Li-Effect is very different from the classical (inverse)
Gertsenshtein-Effect. With the Li-Effect, a gravitational wave transfers energy to a
separately generated electromagnetic (EM) wave in the presence of a static magnetic
field. That EM wave has the same frequency as the GW and moves in the same
direction. This is the "synchro-resonance condition," in which the EM and GW waves are
synchronized (move in the same direction and have the same frequency) and is unlike
the Gertsenshtein- Effect.
The result of the intersection of the parallel and superimposed EM and GW beams,
according to the Li-Effect, is new EM photons moving off in a direction perpendicular to
the beams and the magnetic field directions. Thus, these new photons occupy a
separate reg ion of space (see Figure 12) that can be made essentially noise-free and
the synchro-resonance EM beam itself (in this case a Gaussian beam) is not sensed
there, so it does not interfere with detection of the photons. This Li-Effect was utilized
by Baker (2001) in the design of the Li-Baker HFGW detector and Chinese Patent
(Baker, 2000) of a device to detect HFGWs, the innovative Li-Baker HFGW Detector.
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